At the present time, Internet is a network that has extended all over the world, as there is a growing number of users that access the same from any part of the world, for which it is only necessary to have a terminal equipment with connection to this network. If a user that has this terminal equipment (requesting equipment), wants to be connected with another user (destination equipment), it is necessary to know the numerical IP address of said destination equipment. However, instead of using the IP addresses that are more complicated to retain and manage, names are used to identify each one of the user equipments. This makes necessary the use of a mechanism which, starting from an identification name of the destination equipment with which it is desired to communicate, allows the numerical IP address to be obtained. For this a standardised protocol is employed called the domain naming system (DNS), in which the requesting equipment, before setting up a connection with the destination equipment, queries a DNS server to obtain the IP address. If this server does not have the requested data, it queries another DNS server, or else the actual DNS server that was consulted in the first place, returns the necessary information for querying another DNS server to obtain the desired information. This process can be repeated successively until the IP address is obtained, for which reason the requesting equipment should have the address in store of at least one DNS server, starting from which it will be possible to obtain the IP address of the destination equipment with which it is desired to set up a connection.
The identification names of the terminal equipments are represented by labels separated by dots, so that each one of these labels represents a domain in the network. These domains are tree-structured, so that when a DNS server is consulted, and the latter does not have the required information, it knows what DNS server should be consulted by analysing the different domains of the name, since each server possesses information of an area of the network.
The information that the server queries is stored in an internal database called “Master Files”, so that these databases are distributed over the different DNS servers, as each one of them has information of an area of the network. The information that these databases contain refers to the identification names and IP addresses of each of the user terminals of the network.
The DNS protocol is formed by a header, a field to make the query, another for the answer, another to request authorization, and a last one to include additional information. In each of these fields a series of standardised parameters is included, among which should be mentioned the parameter QNAME that is part of the query field, and which contains the identification name of the destination equipment of which the information is requested, or the parameter RDATA that contains the information that has been requested.
In a mobile telephony or data network, various databases exist with information regarding different client equipments of said network, and due to the advance of information technologies, there is an increasing tendency toward combining telephony and data networks, for which reason it is becoming necessary to have access, in real time, to information of the terminal equipments of said networks to which presently access is only possible within the particular network in question. At the present time no system exists that allows access to different databases in order for example to be able to acquire information, through Internet, of a subscriber of a mobile telephony network or of a data network.